| Setcreasea purpurea Boom.,a Cu-tolerant and Cu-hyperaccumulating ecotype, was found in Dexing copper mining area in Jiangxi Province which is the biggest copper mine in china.Our studies were focus on the Cu-hyperaccumulating mechanism of Setcreasea purpurea Boom.by hydroponic approach,related enzyme analysis,ICP-AES element determination,differential centrifugation and ultarcentrifugation and molecular biology technology.The main results obtained were summarized as follows:Setcreasea purpurea Boom.has the ability to hyperaccumulate Cu.When the supply of Cu was 1000μmol·L-1,the Cu concentration in shoots and roots was up to 1105 and 1210 mg·kg-1DW,respectively.Copper uptake and translocating efficiency of Setcreasea purpurea Boom.depended on the Cu concentration in nutrient solution. and remarkably increased when Cu was over 250μmol·L-1.At different Cu concentration,the uptake and accumulating of Setcreasea purpurea Boom.for necessary nutrient elements kept normal and the concentration of necessary nutrient elements made normal plant species grow.The Cu concentration from 100μmol·L-1 to 250μmol·L-1 obviously promoted the plant growth.High copper concentration has significant influence on the content of protein and component of amino acid in root and shoot.By means of differential centrifugation,the studies on copper distributing character in subcell of Setcreasea purpurea Boom.showed that Cu content mainly distributed in cell wall and Cu content in chloroplast was a majority of whole leaf Cu content.When Setcreasea purpurea Boom.was in the hydroponic solution with high Cu concentration or lengthen culture time,Cu in the root cell distributed more to cell wall and less to chloroplast,but the reverse was in the leaf cell.Cu occurrence characteristic in root and leaf researched by chemical agent order extraction and enzymatic hydrolysis.The results indicated that Cu in leaf mostly combined with amino acid,small molecular pigment,protein,amylose,etc and Cu in root mainly combined with cellulose,membrane banding protein in cell wall.About 60%of banding-Cu combined with cellulose and/or pectin could be dissolved by cellulase and dissociation enzyme.Main parameter of antioxidation system under different Cu levels supplied in nutrient solution were determined and analized.The activities of active oxygen and APX,GPX,CAT and SOD of free radical in root were higher than that in leaf.The activities of APX,GPX,SOD and antioxidation enzymes increased obviously When Cu concentration was over 250μmol,but differed when under 250μmol·L-1.However, CAT activity was decreased with the increase of Cu concentration.GR activities in root and leaf at the supply of 100 and 250μmol·L-1 Cu were remarkably higher than that at other Cu level,and GSH content was comparatively high at the supply of 250μmol·L-1 Cu;proline content in root was correlated linearly to the Cu supplied level and in leaf was negative correlated linearly to the Cu supplied level.Plasma membrane permeability and membrane lipid peroxidation were researched,suggesting that Setcreasea purpurea Boom.was at the shortage of Cu when Cu supply below 50μmol·L-1 and on copper toxic stress when Cu supply over 250μmol·L-1. Photosynthesis and transpiration rate experiments and root system activity research indicated that Setcreasea purpurea Boom.grew well at the high Cu level.Due to its fast growth rate and high Cu-accumulating ability,from a phytoremediation perspective,accumulating ecotype of Setcreasea purpurea Boom.is a potential plant species for Cu removal from contaminated soils.
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